1. Field of the Invention
This invention relates to blowout preventers for use in oil and gas well operations. More particularly, the invention relates to a ram blowout preventer. Still more particularly, the invention relates to a ram blowout preventer which is designed for a given pressure rating and vertical bore size to be as compact and light as reasonably possible.
2. Description of the Prior Art
Ram blowout preventers for use in the oil and gas industry are generally well known. Conventional ram blowout preventers have two or more ram assemblies for fitting about a pipe within the bore of the blowout preventer body to close off the annulus between the pipe and bore or for abutting with one another to close off an open bore. In a ram blowout preventer of this type, the ram assemblies are adapted in their closed position to form a continuous seal with one another across their front faces and across their tops. Sealing across the tops between the ram assemblies and the upper surface of the horizontal bore of the body is accomplished by means of a top seal. The packer in the face of the ram assembly in cooperation with the top seal forms a continuous sealing surface which is effective in sealing off well bore pressure after the ram assemblies are closed.
U.S. Pat. No. 3,102,709 issued in the name of Herbert Allen describes one prior art ram sealing assembly. In that assembly a top seal is provided which extends across the top of the ram member and sealing material is provided along the side of the assembly by the packer and the top seal. Such a ram assembly in cooperation with its horizontal bore seals along the sides of the horizontal ram blowout preventer bore requiring close tolerance machining of a large part of the ram bore. Such machining of a blowout preventer body may raise the manufacturing cost considerably.
Another ram blowout preventer structure is disclosed in U.S. Pat. No. 3,434,729 issued in the name of D.U. Shafer, et al. Illustrated in that patent is a ram assembly which provides for side support of the sealing elements within the ram assembly itself resulting in extra width of the ram. Such extra width of the ram consequently results in wider ram bores and correspondingly large ram blowout preventer bodies.